This effort is a collaboration with Prof. C. Amrhein of the UCR Environmental Sciences department, who is intimately acquainted with the chemical problems associated with environmental cleanup. This unique collaboration provides a basis from which investigations of the basic surface chemistry and physics relevant to environmental cleanup can be addressed.  The particular choice of surface reactions to study is motivated by bulk chemical studies that are carried out in parallel in Prof. Amrhein's lab. The surface studies focus on both the fundamental adsorption of the reactants and the delineation of the chemical reaction mechanisms which lead to the reduction and removal of contaminants from wastewaters and groundwaters. Initially, model systems were investigated in UHV using our existing array of surface analytical techniques. Further work will incorporate the use of a novel wet reaction cell that will enable surface science techniques to probe samples after reaction in aqueous solution.

The first project involved studies of redox chemistry at iron and iron oxide surfaces. In an effort to remove trace contaminants from wastewaters and groundwaters, elemental iron is being used, on an experimental basis, for the reductive dechlorination of solvents and the removal of toxic trace elements, such as Se, Cr and U. Both in situ reactive barriers and above-ground reactors are being developed for this purpose, as illustrated in the figure. However, the design and operation of these treatment systems requires a detailed process-level understanding of iron/contaminant interactions. Most previous studies of these reactions have focused on macroscopic measurements, and consequently very little is known about the basic surface chemical reactions of these toxic elements and solvents with the iron. We are addressing these issues via fundamental investigations of the interactions of the relevant chlorinated solvents, trace elements, and trace element-containing compounds with single- and poly-crystalline Fe surfaces. This work is providing a fundamental physical and chemical understanding of these interactions, which is critical for the development of cleanup techniques and procedures.